[Wedge]

A very high impedance mismatch could stress the trafos to overheat.

 

[RedBull]

As far as I remember, Skylab did mentioned that connecting HE-6 to the speaker terminal give best result, but not so good with LCD-2 as it increases noise floor.  Maybe he revise his statement Skylab will clarify.

 

[Skylab]

It SOUNDS good, but I was warned it might damage the output transformer over time, so I stopped doing it.

 

[Torero]

How long must i burn in the CS300x?

 

[RedBull]

Quote:

It SOUNDS good, but I was warned it might damage the output transformer over time, so I stopped doing it.

Just for my knowledge, do you know why is it?  I thought the speaker tap is designed to deliver 4 or 8 ohms and 50 ohms load should be easy peazy? no?

 

[googleli]

Tried using Mullards for both 12AX7s and EL84s today (both sets from the '50s). For acoustics, the combination sounds great, but for pop music, the bass sounds incredibly slow and a bit fat even on my Monitor Audio speakers. Sounds quite horrible on the already fat LCD2's (Rev 1) bloated bass range - so I switched back the 12AX7s to the Amperex Bugleboy (also 1950's) and everything is fine again. I also got the Sylvania 12AX7s and the pair sounds more balanced than with the Amperex on my speakers, but for the LCD2s, I prefer the Amperex due to LCD2's rolled off highs (again the Rev 1, so the same combination may not suit the Rev 2).
 
Conclusion: in my experience the following combination is the best for LCD2 Rev 1:
 
12AX7: Amperex Bugleboy Long Plate D-getter 1950's
 
EL84:  Mullard 1950's - they are quite rare so get whatever you can as long as they are from 1950's.  
 
FYI I also have and tried the following tubes - Sovtek 12AX7s and EL84s (stock tubes from Leben), Gold Lion EL84s, Mazda 12AX7s, Telefunken smooth plates, Sylvania 12AX7 and Brimars. 

 

[Skylab]

Quote:

How long must i burn in the CS300x?

I thought 10-20 hours was plenty.
 


Quote:

Quote:

Just for my knowledge, do you know why is it?  I thought the speaker tap is designed to deliver 4 or 8 ohms and 50 ohms load should be easy peazy? no?

Supposedly that is not ENOUGH of a load for the transformer.
 

 

[Wedge]

I really like using 5751s in my Leben.

 

[Skylab]

I've used exclusively 5751's for the driver tubes.

 

[dminches]

I have used 5751s exclusively because Rob told me to!

 

[Wedge]

Sylvania Gold Brand 3 Mica Grey Plates, as well as the Black Plates, have pretty much what I've been using in my Leben.  They have a real smooth, dynamic, extended sound to me.  I love them. I'm torn on the output tubes, I had Mullards in for a while, now I have Tungsram E84Ls in.  I have bounced back and forth between these and for a little while I had Sylvania 6BQ5s which were a tad less smooth, and little more neutral.

 

[RedBull]

Quote:

Supposedly that is not ENOUGH of a load for the transformer.
 

Hmm, sorry, I'm an electronic noob, so the transformer can't release energy large enough, thus will damage the transformer, is that the correct analogy?

 

[Skylab]

I believe so, RedBull, but it was a concept I also had a hard time getting my arms around. It is an issue for sure related just to output transformers.

 

[RedBull]

Thanks Rob.

 

[Sharklordy]

Is this amp still the best for lcd2 rev2?